The compound used as the efficacious or active ingredient in the present invention is generally called ketorolac and the formal chemical name thereof is (.+-.)-5-benzoyl-2,3-dihydro-1H-pyrrolidine-1-carboxylic acid (or 5-benzoyl-1,2-dihydro -3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acid). Ketorolac was first synthesized by Syntex (U.S.A.) and disclosed as a compound having a remarkable anti-inflammatory analgesic effect in Japanese Patent Gazette No. Sho 62-54109 (54109/1987). Examples of the preparations containing ketorolac or its salt include an internal remedy and an injection disclosed in Japanese Patent Laid-Open Gazette No. Sho 61-191686 (191686/1986), and eye drops for local application described in Japanese Patent Laid-Open Gazette No. Sho 58-172314 ( 172314/1983 ).
Thus, only pharmaceutical preparations such as internal remedies, injections or eye drops each containing ketorolac were disclosed in the prior art, but no plasters containing ketorolac were suggested at all. Therefore, neither description of the fomentation containing ketorolac nor description of its formulation was found at all. Thus it was extremely difficult to anticipate whether ketorolac is usable as the efficacious or active ingredient of a fomentation and an excellent fomentation can be thus developed.
As described above, no attention was directed to the fomentation containing ketorolac as the active ingredient and no investigation was made thereon heretofore. As a matter of course, such a fomentation has not been put into practical use as yet.
Thus the inventors were interested in ketorolac having a remarkable anti-inflammatory analgesic effect in such conventional preparations as above. After their intensive investigations made in an attempt to obtain a fomentation in which ketorolac exhibits a remarkable efficacious effect, the inventors have foundan unexpected fact that ketorolac is difficultly soluble in a fomentation base and is enclosed in the form of crystals therein. The inventors have also found there are raised physical problems of, for example, the compatibility of ketorolac with the base, the stability of the active ingredient, and the reduction in exertion of the medicinal effect due to a decrease in releasability of the active ingredient from the base and percutaneous absorbability of said ingredient. It has been thus found that the development of a desired ketorolac-containing fomentation is difficult unless there are solved problems of the pharmaceutical manufacturing, formulation, design and exertion of the medicinal effect of the desired fomentation.